Alloying Elements Transition Into the Weld Metal When Using an Inventor Power Source

The temperature distribution over the surface of the welded 12Kh18N10T steel plates using the inventor power source ARC-200 has been calculated. In order to imitate multipass welding when conducting the thermal analysis the initial temperature was changed from 298K up to 798K in 100K increments. It has been determined that alloying elements transition into the weld metal depends on temperature. Using an inventor power source facilitates a uniform distribution of alloying elements along the length and height of the weld seam

Geochemical Constraints for the Bulk Composition of the Moon

© 2018, Pleiades Publishing, Ltd. Abstract: The bulk composition of the silicate Moon (crust + mantle, BSM) is determined on the basis of inversion of gravitational and seismic data. It is shown that the mantle refractory oxides form two different groups depending on the thermal state. By the bulk Al2O3 content of ~3.0–4.6 wt %, the cold BSM models span the range of Al2O3 content of the silicate Earth (Bulk Silicate Earth, BSE), whereas the hot BSM models are significantly enriched in the Al2O3 content of ~5.1–7.3 wt % (Al2O3 content of ~1.2–1.7 × BSE) relative to BSE. In contrast, apart from the distribution of temperature, both BSM models are characterized by almost constant values of bulk FeO contents (~12.2–13.2 wt %) and MG# values (80.0–81.5), which are strongly distinct from those for BSE (~8 wt % FeO and 89 MG#). The results show that, for the geophysically possible distribution of temperatures, the silicate fraction of the Moon is enriched in FeO and depleted in MgO relative to BSE

Effect of High-Pressure Torsion on the Microstructure and Magnetic Properties of Nanocrystalline CoCrFeNiGax (x = 0.5, 1.0) High Entropy Alloys

In our search for an optimum soft magnet with excellent mechanical properties which can be used in applications centered around “electro mobility”, nanocrystalline CoCrFeNiGax (x = 0.5, 1.0) bulk high entropy alloys (HEA) were successfully produced by spark plasma sintering (SPS) at 1073 K of HEA powders produced by high energy ball milling (HEBM). SPS of non-equiatomic CoCrFeNiGa₀.₅ particles results in the formation of a single-phase fcc bulk HEA, while for the equiatomic CoCrFeNiGa composition a mixture of bcc and fcc phases was found. For both compositions SEM/EDX analysis showed a predominant uniform distribution of the elements with only a small number of Cr-rich precipitates. High pressure torsion (HPT) of the bulk samples led to an increased homogeneity and a grain refinement: i.e., the crystallite size of the single fcc phase of CoCrFeNiGa₀.₅ decreased by a factor of 3; the crystallite size of the bcc and fcc phases of CoCrFeNiGa—by a factor of 4 and 10, respectively. The lattice strains substantially increased by nearly the same extent. After HPT the saturation magnetization (Ms) of the fcc phase of CoCrFeNiGa₀.₅ and its Curie temperature increased by 17% (up to 35 Am²/kg) and 31.5% (from 95 K to 125 K), respectively, whereas the coercivity decreased by a factor of 6. The overall Ms of the equiatomic CoCrFeNiGa decreased by 34% and 55% at 10 K and 300 K, respectively. At the same time the coercivity of CoCrFeNiGa increased by 50%. The HPT treatment of SPS-consolidated HEAs increased the Vickers hardness (Hv) by a factor of two (up to 5.632 ± 0.188) only for the non-equiatomic CoCrFeNiGa₀.₅, while for the equiatomic composition, the Hv remained unchanged (6.343–6.425 GPa)

Refractory TaTiNb, TaTiNbZr, and TaTiNbZrX (X = Mo, W) high entropy alloys by combined use of high energy ball milling and spark plasma sintering: Structural characterization, mechanical properties, electrical resistivity, and thermal conductivity

Refractory TaTiNb, TaTiNbZr, and TaTiNbZrX (X = Mo, W) high entropy alloys were synthesized by combined use of high energy ball milling (HEBM) and spark plasma sintering (SPS). Powders of predominantly bcc TaTiNbZrX (X = Mo, W) refractory high entropy alloys (RHEAs) were successfully prepared by short-term HEBM (60 min) and then SPS-consolidated at 1373 K for 10 mi

Assessment of fatigue damage to aircraft glass using digital holography methods

The purpose of this work is to test the digital holography method for determining the depth of fatigue surface defects of the "silver" type of aviation organic glass caused by cyclic mechanical overloads, as well as the impact of aggressive substances. To study the fatigue defects of aviation organic glass, a digital holographic camera was used, the configuration of which is an axial scheme for recording digital Gabor holograms. During the experiment, the possibility of using the digital holography method to determine the characteristic transverse dimensions of surface defects in aircraft glazing parts and longitudinal dimensions was shown. The work carried out and the created model of the digital holographic camera show the potential possibility of creating a method for checking with a given accuracy the elements of the aircraft glazing for the presence of surface damage and assessing their impact on flight safety

Наноструктурированный градиентный материал на основе псевдосплава Cu-Cr-W, полученный методами высокоэнергетической механической обработки и искрового плазменного спекания

This study was conducted to obtain nanostructured mechanically activated composite particles from immiscible metals Cu, Cr and 5÷70 wt.% W, nanostructured bulk materials based on them and Cu / Cu—Cr—W nanostructured gradient material with different tungsten content by combined short-term (up to 150 min) high-energy ball milling (HEBM) and spark plasma sintering (SPS). Cu— Cr—W mechanically activated composites were obtained by HEBM of Cu + Cr + (5÷70 wt.%)W powder mixtures in the Activator-2S ball planetary mill at the rotating speed of 1388 rpm for the grinding chamber and 694 rpm for the planetary disk in an argon atmosphere for 150 min. Cu—Cr—W mechanically activated composite particles were consolidated by SPS in the temperature range of 800— 1000 °C at a pressure of 50 MPa for 10 min. The nanostructured gradient sintered material based on Cu—Cr—W pseudo alloys was pressed layer by layer in the following sequence (from pure copper to pseudo alloy with increasing tungsten content): Cu / Cu—Cr—5%W / Cu—Cr—15%W / Cu—Cr—70%W and sintered at 800 °C for 10 min. The crystal structure, microstructure, and properties of Cu— Cr—W mechanically activated composites and consolidated materials based on them were studied depending on production conditions. It was shown that the nanostructure formed in mechanically activated composites at the short-term HEBM stage (up to 150 min) was preserved for all Cu—Cr—W (5÷70 wt.% W) compounds after SPS. Based on SEM and EDX, refractory particles of W (d ~ 20÷100 nm) and Cr (d ~ 20÷50 nm) were uniformly distributed in the material volume (in the copper matrix). The hardness of Cu—Cr—W (15 wt.% W) bulk samples obtained from nanostructured powder mixtures (after 150 min HEBM) by SPS at 800 °C was approximately 6 times higher than the hardness of samples sintered from the mixture of starting components (without HEBM). For the Cu—Cr—70%W nanostructured compound (tsps = 1000 °С) the hardness value was ~3 times higher than that for microcrystalline analogues. The highest re­lative density of 0.91 was achieved for Cu—Cr—15%W and Cu—Cr—70%W samples. Electrical resistivity for nanostructured Cu—Cr—W composites were 2 times higher than for microcrystalline samples. Apparently, this is due to an increase in grain boundaries and various defects accumulated in the material at the HEBM stage. The obtained results show that combined short-term HEBM and subsequent SPS is a promising way to produce nanocrystalline Cu—Cr—W composites and gradient materials based on them.В настоящей работе сочетанием методов непродолжительной (до 150 мин) высокоэнергетической механической обработки (ВЭМО) и искрового плазменного спекания (ИПС) были получены наноструктурированные механокомпозиты из несмешивающихся между собой металлов Cu, Crи 5÷70 мас.% W, наноструктурированные консолидированные материалы на их основе и наноструктурированный градиентный материал Cu / Cu—Cr—W с различным содержанием вольфрама. Для получения механокомпозитов Cu—Cr—Wпроводилась ВЭМО порошковых смесей Cu+ Cr+ (5÷70мас.%)\W в шаровой планетарной мельнице Активатор-2S при скорости вращения барабанов 1388 об/мин и планетарного диска 694 об/мин в среде аргона в течение 150 мин. Консолидация механокомпозитов Cu—Cr—W осуществлялась методом ИПС при температурах 800—1000 °С, давлении 50 МПа в течение 10 мин. Наноструктурированный градиентный спеченный материал на основе Cu—Cr—W-псевдосплавов запрессовывался послойно в следующей последовательности (от чистой меди к псевдосплаву с увеличением массовой доли вольфрама): Cu / Cu— Cr—5%W / Cu—Cr—15%W / Cu-Cr-70%W и спекался при температуре 800 °C в течение 10 мин. Исследованы кристаллическая структура, микроструктура и свойства механокомпозитов Cu—Cr—W и консолидированных материалов на их основе в зависимости от условий получения. Показано, что наноструктура, сформированная в механокомпозитах на стадии непродолжительной ВЭМО (до 150 мин), сохранялась после ИПС для всех составов Cu—Cr—W(5÷70 мас.% W). По данным СЭМ и ЭДС тугоплавкие частицы W (d~ 20÷100 нм) и Cr (d~ 20÷50 нм) равномерно распределены в объеме материала (в медной матрице). Твердость консолидированных образцов Cu—Cr—15%W, полученных из наноструктурированных порошковых смесей (после 150 мин ВЭМО) методом ИПС при t= 800 °С в ~6 раз превышает твердость образцов, спеченных из смеси исходных компонентов (без ВЭМО). Для наноструктурированного состава Cu—Cr—70%W(tипс = 1000 °С) значение твердости было в ~3 раза выше, чем у ми­крокристаллических аналогов. Образцы Cu—Cr—15%W и Cu—Cr—70%Wобладали наибольшей относительной плотностью — до 0,91. Удельное электрическое сопротивление наноструктурированных композитов Cu—Cr—W приблизительно в 2 раза превышало этот показатель для микрокристаллических образцов. Это может быть обусловлено увеличением гра­ниц зерен и накоплением различного рода дефектов в материале на стадии ВЭМО. Полученные результаты показывают перспективность использования сочетания методов кратковременной ВЭМО и последующего ИПС для создания консолидированных нанокристаллических композитов Cu—Cr—Wи градиентных материалов на их основе

PhysEth1107004KronrodLO.fm

Abstract-We model the internal structure of the Moon, initially homogeneous and later differentiated due to partial melting. The chemical composition and the internal structure of the Moon are retrieved by the Monte Carlo inversion of the gravity (the mass and the moment of inertia), seismic (compressional and shear velocities), and petrological (balance equations) data. For the computation of phase equilibrium relations and physical properties, we have used a method of minimization of the Gibbs free energy combined with a Mie Gr@uneisen equation of state within the CaO FeO MgO Al 2 O 3 -SiO 2 system. The lunar models with a different degree of constraints on the solution are considered. For all models, the geophysically and geochemically permissible ranges of seismic velocities and concentrations in three mantle zones and the sizes of Fe 10%S core are estimated. The lunar mantle is chemically stratified; different mantle zones, where orthopyroxene is the dominant phase, have different concentrations of FeO, Al 2 O 3 , and CaO. The silicate portion of the Moon (crust + mantle) may contain 3.5-5.5% Al 2 O 3 and 10.5-12.5% FeO. The chemical boundary between the middle and the lower mantle lies at a depth of 620-750 km. The lunar models with and without a chemical boundary at a depth of 250-300 km are both possible. The main parameters of the crust, the mantle, and the core of the Moon are estimated. At the depths of the lower mantle, the P and S velocities range from 7.88 to 8.10 km/s and from 4.40 to 4.55 km/s, respectively. The radius of a Fe 10%S core is 340 ± 30 km. In the present work, we suggest a new model of the constitution and internal structure of the Moon. This model is based on the hypothesis of the magma ocean; it involves modern mathematical processing of the P and S travel time data Keywords PETROLOGICAL AND GEOPHYSICAL CONSTRAINTS Models of the Magma Ocean The early differentiation of the Moon with the for mation of the continental feldspar crust, which has a thickness of about 50-60 km and ~25% Al 2 O 3 , as well as the age of the lunar rocks, have motivated the hypothesis of the Magma Ocean. The latter is com monly understood as the outer lunar shell, which had undergone partial melting By analyzing the thermoelastic stresses, Solomon [1986] showed that there is no tectonic evidence for a large scale expansion or compression of the Moon over the past four billion years (after a period of its intense bombardment). He estimated the lunar radius to have been changed by about a kilometer, which dis agrees with the concept of extensive melting. The set of petrological, geochemical, and geophysical data offers no reasons to believe that the Moon had ever been totally molten and formed a continuous magma ocean. This is also supported by the lunar asymmetry (the center of figure of the Moon is offset by 2 km from the center of mass). By analyzing the volumetric effects of differentiation of the Moon, The melting depth of 500-600 km well agrees with the experimental data on the crystallization of lunar basalts and green and picrite glass [Ringwood and Ess ene, 1970; Some information on the thickness of MO can be inferred from the geophysical data. The results of the Apollo mission infer that one or a few seismic bound aries exist in the mantle at a depth of 400-750 km In our works Seismic Data The seismic data are a kind of the Rosetta Stone for understanding the internal structure of the Moon. Processing the data obtained in the experiment that lasted for eight years (1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977) and included seis mic measurements at four landing sites of Apollo 12, 14, 15, and 16 missions revealed the seismic structure of the lunar interiors shown in The mathematical processing of travel times of P and S waves suggests a zonal structure of the lunar mantle